Tag Archives: #civilization

Life in These Star-systems Could Have Spotted Earth (Planetary Science)

Scientists at Cornell University and the American Museum of Natural History have identified 2,034 nearby star-systems – within the small cosmic distance of 326 light-years – that could find Earth merely by watching our pale blue dot cross our sun.

That’s 1,715 star-systems that could have spotted Earth since human civilization blossomed about 5,000 years ago, and 319 more star-systems that will be added over the next 5,000 years.

Exoplanets around these nearby stars have a cosmic front-row seat to see if Earth holds life, the scientists said in research published June 23 in Nature.

“From the exoplanets’ point-of-view, we are the aliens,” said Lisa Kaltenegger, professor of astronomy and director of Cornell’s Carl Sagan Institute, in the College of Arts and Sciences.

“We wanted to know which stars have the right vantage point to see Earth, as it blocks the Sun’s light,” she said. “And because stars move in our dynamic cosmos, this vantage point is gained and lost.”

Kaltenegger and astrophysicist Jackie Faherty, a senior scientist at the American Museum of Natural History and co-author of “Past, Present and Future Stars That Can See Earth As A Transiting Exoplanet,” used positions and motions from the European Space Agency’s Gaia eDR3 catalog to determine which stars enter and exit the Earth Transit Zone – and for how long.

“Gaia has provided us with a precise map of the Milky Way galaxy,” Faherty said, “allowing us to look backward and forward in time, and to see where stars had been located and where they are going.”

Of the 2,034 star-systems passing through the Earth Transit Zone over the 10,000-year period examined, 117 objects lie within about 100 light-years of the sun and 75 of these objects have been in the Earth Transit Zone since commercial radio stations on Earth began broadcasting into space about a century ago.

“Our solar neighborhood is a dynamic place where stars enter and exit that perfect vantage point to see Earth transit the Sun at a rapid pace,” Faherty said.

Included in the catalog of 2,034 star-systems are seven known to host exoplanets. Each one of these worlds has had or will have an opportunity to detect Earth, just as Earth’s scientists have found thousands of worlds orbiting other stars through the transit technique.

By watching distant exoplanets transit – or cross – their own sun, Earth’s astronomers can interpret the atmospheres backlit by that sun. If exoplanets hold intelligent life, they can observe Earth backlit by the sun and see our atmosphere’s chemical signatures of life.

The Ross 128 system, with a red dwarf host star located in the Virgo constellation, is about 11 light-years away and is the second-closest system with an Earth-size exoplanet (about 1.8 times the size of our planet). Any inhabitants of this exoworld could have seen Earth transit our own sun for 2,158 years, starting about 3,057 years ago; they lost their vantage point about 900 years ago.

The Trappist-1 system, at 45 light-years from Earth, hosts seven transiting Earth-size planets – four of them in the temperate, habitable zone of that star. While we have discovered the exoplanets around Trappist-1, they won’t be able to spot us until their motion takes them into the Earth Transit Zone in 1,642 years. Potential Trappist-1 system observers will remain in the cosmic Earth transit stadium seats for 2,371 years.

“Our analysis shows that even the closest stars generally spend more than 1,000 years at a vantage point where they can see Earth transit,” Kaltenegger said. “If we assume the reverse to be true, that provides a healthy timeline for nominal civilizations to identify Earth as an interesting planet.”

The James Webb Space telescope – expected to launch later this year — is set to take a detailed look at several transiting worlds to characterize their atmospheres and ultimately search for signs of life.

The Breakthrough Starshot initiative is an ambitious project underway that is looking to launch a nano-sized spacecraft toward the closest exoplanet detected around Proxima Centauri – 4.2 light-years from us – and fully characterize that world.

“One might imagine that worlds beyond Earth that have already detected us, are making the same plans for our planet and solar system,” said Faherty. “This catalog is an intriguing thought experiment for which one of our neighbors might be able to find us.”

The Carl Sagan Institute, the Heising Simons Foundation and the Breakthrough Initiatives program supported this research.


Reference: Kaltenegger, L., Faherty, J.K. Past, present and future stars that can see Earth as a transiting exoplanet. Nature 594, 505–507 (2021). https://doi.org/10.1038/s41586-021-03596-y


Provided by Cornell University

Research Unlocks New Information About Reading Through Visual Dictionary in the Brain (Neuroscience)

The uniquely human ability to read is the cornerstone of modern civilization, yet very little is understood about the effortless ability to derive meaning from written words. Scientists at The University of Texas Health Science Center at Houston (UTHealth) have now identified a crucial region in the temporal lobe, know as the mid-fusiform cortex, which appears to act as the brain’s visual dictionary. While reading, the ability of the human brain to distinguish between a real word such as “lemur” and a made-up word like “urmle” appears to lie in the way that region processes information.

Nitin Tandon, MD, and his research team identified a crucial region in the temporal lobe which appears to act as the brain’s visual dictionary. (Photo by James LaCombe)

These findings were published today in Nature Human Behavior.

“How much the mid-fusiform responds to a word and how quickly it can distinguish between a real and made-up word is highly dependent on how frequently the real word is encountered in everyday language,” said Nitin Tandon, MD, senior author, professor and vice chair in the Vivian L. Smith Department of Neurosurgery at McGovern Medical School at UTHealth. “So short, common words like ‘say’ can be identified quickly but long, infrequent words like ‘murmurings’ take longer to be identified as real words.”

For the study, Nitin Tandon and postdoctoral fellow Oscar Woolnough, PhD, the lead author, used recordings from patients who had electrodes temporarily placed in their brains while undergoing treatment for epilepsy. These recordings were then used to create a visual representation of the early neural processing of written words.

They found that this region, which has been overlooked in many previous studies of reading, compares incoming strings of letters encountered while reading with stored patterns of learned words. After words are identified in this area of the brain, this information is spread to other visual-processing regions of the brain.

“Since word frequency is one of the main factors that determines how fast people can read, it is likely that the mid-fusiform acts as the bottleneck to reading speed,” Tandon said. “We showed that if we temporarily disrupt activity in the mid-fusiform cortex using briefly applied electrical pulses, it causes a temporary inability to read, a dyslexia, but doesn’t disrupt other language functions like naming visual objects or understanding speech.”

Tandon said the study serves to improve understanding of how people read and can help people with reading disorders such as dyslexia, the most common learning disability.

Tandon is co-director of the Texas Institute for Restorative Neurotechnologies at UTHealth, faculty in UTHealth Neurosciences and MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, and an attending physician at Memorial Hermann-Texas Medical Center. UTHealth co-authors were Patrick S. Rollo, research associate, and Kiefer J. Forseth, an MD/PhD student at MD Anderson UTHealth Graduate School.

Other co-authors were from the University of Bucharest, Romania; Universite Paris-Sud and Universite Paris-Saclay, France; Johns Hopkins Medical Center, Baltimore; Rice University, Houston; and College de France, Paris.

The study was funded by the National Institute of Neurological Disorders and Stroke and the National Institute on Deafness and Other Communication Disorders, part of the National Institutes of Health, via the BRAIN Initiative (grant NS098981).

References: http://dx.doi.org/10.1038/s41562-020-00982-w

Provided by University of Texas Health Science Center at Houston

Alberto Callebro Suggested Several Candidate Sources For WOW Signal (Astronomy)

Alberto Caballero identified and suggested several candidate sources for the WOW! Signal. In the region ranging from 19h25m31s ± 10s to −26°57′ ± 20′, and 19h28m22s ± 10s to −26°57′ ± 20′, a total of 66 G and K-type (i.e. our sun-like) stars were found by him in the Gaia DR2 archive. Out of this sample, two stars are close to the celestial distance with the highest chance of having a communicative civilization, according to Maccone’s mathematical estimations.

Figure 1: In red, the two regions where the WOW! Signal could have originated. Source: Pan-STARRS/DR1

As of October 2020, the WOW! Signal remains the strongest candidate SETI signal. It has been suggested that the signal was produced by hydrogen clouds from Comets 266/P Christensen and P/2008 Y2. However, this hypothesis has been dismissed by the scientific community, and the source of the signal remains unknown. Despite the WOW! Signal never repeated, the key aspect was its duration. The signal lasted for 72 seconds, but since this was the maximum amount of time that the Big Ear radio telescope was able to observe, it is likely that the signal would have lasted longer. The main problem, however, is that the signal never repeated. Follow-up observations of the area conducted by many observatories during several years never detected another signal. Nonetheless, the fact that the signal never repeated, does not necessarily discard that it was produced by extraterrestrial intelligence.

“In fact, if we analyse the history of (the few) radio signals that humanity have sent to several targets in the hope of contacting a civilization, none of those transmissions had a long duration or were repeatedly sent for a long time. An extraterrestrial civilization could have opted to behave in a similar manner.”, said Alberto Callebro.

According to Alberto, the only potential Sun-like star in all the WOW! Signal region appears to be 2MASS 19281982-2640123. Despite this star is located too far for sending any reply in the form of a radio or light transmission, it could be a great target to make observations searching for exoplanets around the star.

Figure 2: The only potential Sun-like star found in the WOW! Signal region with the available data
Source: PanSTARRS/DR1

However, more information such as metallicity, age, and presence or not of stellar companions is needed in order to determine that 2MASS 19281982-2640123 is indeed a Sun-like star. Moreover, another 14 potential Sun-like stars in the WOW! Signal region were found in the Gaia Archive, but the estimations on their luminosity were unknown.

Figure 3: List of G and early-to-mid K type stars in the WOW! Signal region, positive feed horn
Source: ESA
Figure 4: List of G and early-to-mid K type stars in the WOW! Signal region, negative feed horn
Source: ESA

He also mention that the signal could have come from any of the 66 G and K-type stars, a star that only meets one or two of the parameters set for the optimistic sample (in the WOW! Signal region, a total of 550 stars with a temperature between 4,450 and 6,000 K were found, but no information about their luminosity and radius is available), stars that are not included in the Gaia Archive, a star that is too dim to image with current technology, an extragalactic source, or any other origin.

In any case, since all these stars are located in the same part of the sky, it is ideal to search for exoplanets in the whole region where the WOW! Signal could have come from.

References: Alberto Caballero, “An approximation to determine the source of the WOW! Signal”, pp. 1-6, ArXiv, 2020. https://arxiv.org/abs/2011.06090v1

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Advanced Alien Civilization May Get Their Energy From Dyson Sphere (Astronomy)

It’s a fact that the more advanced humanity gets, the more energy we need. Between 1965 and 2015, the world’s energy consumption nearly tripled. Who knows how much energy we’ll need in another 50, 100, 1,000 years? Scientists assume it’s no different for alien civilizations. There will be a point when the energy resources they can tap from their planet’s surface are no longer enough. Never fear — they’ll probably have a Dyson sphere.

Dyson spheres are the stuff of futuristic science fiction, so it might surprise you to learn that they were first conceived way back in the 1930s. In his 1937 sci-fi novel “Star Maker,” Olaf Stapledon wrote about an advanced alien community that “began to avail itself of the energies of its stars upon a scale hitherto unimagined. Not only was every solar system now surrounded by a gauze of light traps, which focused the escaping solar energy for intelligent use, so that the whole galaxy was dimmed, but many stars that were not suited to be suns were disintegrated, and rifled of their prodigious stores of sub-atomic energy.”

Well, it turns out that scientists read sci-fi. Theoretical physicist Freeman Dyson was so inspired by Stapledon’s idea that in 1960, he published a paper in the journal Science laying out why and how an advanced alien civilization might create such a device — and how we might detect it if they did.

Dyson used our own situation as an example. Currently, even our best solar panels can only collect a small fraction of the energy the sun produces, since most of it radiates out into space. But if we could somehow collect all of that energy, we could increase our energy resources by a mind-boggling margin. He also figured that over a few thousand years, we may be able to mine the solar system for supplies roughly equaling the mass of Jupiter. With those supplies, we could conceivably build a “spherical shell” (which he later clarified to be a “loose collection or swarm of objects traveling on independent orbits”) sitting at twice the Earth’s distance from the sun — between what would be left of Mars and Jupiter. That shell, or Dyson sphere, as it’s now called, could theoretically collect every last bit of energy from our home star.

Dyson was quick to point out that he wasn’t suggesting this would happen to us; just that it may have already happened in other solar systems. And if it has, there’s a way to look for it. “The most likely habitat for such beings would be a dark object, having a size comparable with the Earth’s orbit, and a surface temperature of 200 deg. to 300 deg. K,” Freeman wrote. “Such a dark object would be radiating as copiously as the star which is hidden inside it, but the radiation would be in the far infrared.” If astronomers ever find an object that’s dark in visible wavelengths of light but bright in far-infrared wavelengths — dark and hot, basically — bingo. We’ve probably found E.T.

It’s been more than half a century since Dyson proposed this new way of searching for alien life. Have we found anything?

We’ve certainly thought so. In 2015, Tabetha Boyajian discovered a mysterious object that acted kinda weird. Dubbed “Tabby’s star,” this star would experience weird fluctuations in its brightness, sometimes staying constant for a long period of time, other times dimming by a fifth and going bright again, other times dimming and brightening sporadically in rapid succession. You know, the way a star might dim if a Dyson sphere was being built around it.

The star was so mysterious that Boyajian and her team raised more than $100,000 on a Kickstarter to help them study it. In January 2018, they had their answer: dust, probably. The dips in brightness changed depending on the color of light the team was measuring. If it were an alien megastructure like a Dyson sphere, you’d expect all of the colors to be blocked at once.

But just the fact that scientists considered a Dyson sphere within the realm of possibility shows just how viable they believe this idea to be. As for now, we’ll keep looking for dark, hot objects. If there’s a Dyson sphere out there, it might show itself someday.


Matrioshka Brain Is A Computer The Size Of A Solar System (Astronomy)

Imagine a computer the size of a solar system. For power, it would use a Dyson sphere—a solar array that completely surrounds the host star to collect almost all of its energy. That energy-collecting sphere would double as an ultra-powerful computer processor. Once the sphere had collected all the energy it needed, it would pass the excess to another larger Dyson-sphere processor that completely surrounded the first, repeating the process until all of the energy was being used. That’s why this theoretical computer is called a Matrioshka brain: the nested Dyson spheres would resemble matryoshka dolls, or Russian nesting dolls.

Of course, if you surround your star with Dyson spheres, it would be difficult for life on your planet to continue. That’s kind of the point: this Matrioshka brain would be so powerful that a species could upload their entire consciousness into it and live within an alternate universe simulated by the computer. The species itself could die and its planet could be destroyed, but the civilization would live on in a digital world identical to the one it left behind. In fact, many people, including Elon Musk, believe we’re living in a simulation like that at this very moment. This provides one answer to the Fermi Paradox—that is, the question of why we haven’t encountered aliens despite the likelihood that they’re out there. It’s possible that any civilization advanced enough to find us has already decided to abandon reality entirely and upload themselves to a Matrioshka brain.

A civilization that has built a Matrioshka Brain is by definition a Type II civilization on Kardashev scale since a Matrioshka Brain uses all the energy of a star and as a consequence (virtually) all the energy available in its planetary system.

While a megastructure like the Matrioshka Brain would obviously require a huge amount of resources, it’s a very interesting concept: in a way, it can be viewed as the ultimate destiny of a planetary system like our Solar System. Why? Because ultimately, intelligence is “just” a matter of computation. Our brains carry out about a billion billion calculations per second, but a Matrioshka Brain could carry out an amount of calculations that dwarfs that by an unimaginable amount. In that sense, when built and programmed in the right way, a Matrioshka Brain would be the ultimate superintelligence a planetary system can have: it would use all the energy output for its intelligence. What such a star-sized superintelligence could think of and invent is far beyond our imagination. Even the billions of human brains currently alive put together wouldn’t be of any match for such a godly intelligence.

Is a Matrioshka Brain Even Possible?

While they may be theoretically possible to build, Matrioshka Brains come with difficulties. For example, being a rigid structure around a star, it could quite easily drift from its original place relative to its star and crash straight into that star due to the strong gravitational pull, as noted by Kurzgesagt (when talking about Dyson Spheres). However, a more realistic variant might be what we could call a Matrioshka Swarm: a (huge) number of satellites orbiting around the star, each with computational resources powered by the star’s energy output. These computer satellites could wirelessly communicate with each other. This approach is analogous to a Dyson Swarm and it has its advantages: it could be built gradually (one satellite at a time), to name one, and we already know how to put satellites in orbit around a body. A simple form of Matrioshka Swarm could be a Matrioshka Ring: like the rings of Saturn, there would be a ring of computer satellites in orbit around a star.


The Drake Equation Estimates How Many Alien Civilizations Are Out There (Astronomy)

What are the odds that there’s intelligent life beyond our planet? Good news: there’s an equation for that. The Drake Equation estimates how many extraterrestrial civilizations may exist beyond our galaxy. There’s just one catch.

Dr. Frank Drake presented the Drake Equation in 1961. Here it is in all its glory:

N = R* • fp • ne • fl • fi • fc • L

What does that all mean, exactly? It’s a way to say that life is present on a fraction of a fraction of a fraction of the planets in the universe. Let’s break it down:

• N = The number of detectable civilizations in our galaxy. This is the number the equation is trying to find.
• R* = The rate that stars suitable for developing intelligent life are forming.
• fp= The fraction of those stars that have solar systems.
• ne = The number of planets in each of those solar systems that could support life. (See how we’re narrowing that N number down little by little?)
• fl = The fraction of those habitable planets that actually contain life.
• fi = The fraction of those life-bearing planets that actually have intelligent life.
• fc = The fraction of intelligent civilizations that develop a technology that release detectable signs of their existence into space.
• L = The length of time those signals have been transmitting.

Exciting as the possibility of alien life is, you can see how it’s difficult to calculate our chances are of finding it—at least right now. We don’t have exact numbers for most of the equation, so crunching the numbers is a challenge, at best. Still, we can theorize. The equation can result in a broad range of answers depending on how optimistic or informed the user is. Many scientists look at the equation as a useful and tool for the probability of life on other worlds.